Engine starter gearing



sept. 9,1958` c. A. MENDENHALL 2,850,906

y v Y ENGINE STARTER GERING l vFiled May 14, 195e ,e5 a@ ze ,35. ,a4 la Vga/7 az ze 15 "Il I l l F @nvm l l I( z5 l n f l 3; :a zzzeszz I M l gwn-* l@ 4 5 agg INVENTOR; d/f6.5@ WITNESS:

United States Patent ENGINE STARTER GEARIN G Charles A. Mendenhall, Horseheads, N. Y., assignor to Bendix Aviation Corporation, a corporation of Delaware Application May 14, 1956, Serial No. 584,700

7 Claims. (Cl. 74-7) The present invention relates to engine `starter gearing and more particularly to a starter drive of the type in `which a motor driven pinion is automatically traversed into and out of mesh with an engine gear, responsive to energization of the starting motor, and self operation of the engine respectively.

It is an object of the .present invention to provide a novel starter drive of this type which is small in size and economical in construction in relation to the service for `which it is designed.

It is another object to provide such a device in which the pinion, when in idle position, is retracted within the contines of its driving connection.

`lt is another object to provide such a device in which the polar moment of inertia of the axially shifted sub- -assembly is comparatively large, thereby assisting in reliability of traversal under adverse conditions.

It is yanother object to provide such a device incorporating a pinion of small diameter, necessitating its being formed either solid or with a small bore resting on a reduced extension of the power shaft; and providing extraneous means for maintaining the alignment of the pinion during the cranking operation.

Further objects and advantages -will be apparent from the following description taken in connection with the accompanying drawing in which:

lFig. 1 is a `side elevation of a preferred embodiment of the invention partly broken away and in axial section, yshowing the .parts in normal or idle position; and

Fig. 2 is a similar view showing the parts in cranking position.

`In Fig. 1 of the drawing there is illustrated a power shaft 1 on which a vhollow screw .shaft 2 is ixedly mounted 4as by means of a cross pin 3. A pinion 4 is slidably journalled on a reduced extension 5 of the power shaft for movement into and out of mesh with a gear 6 of an engine to be started, the outer end of the power shaft being preferably `supported by :an outboard bearing 7.

A control nut v8 is threaded on the screw shaft, and a sleeve member 9 is rigidly mounted at one end on the pinion 4 as indicated at 11, and is provided with axial slots 12 slidably receiving radial projections 13 yof the control nut to form a splined connection therewith.

A barrel member 14 is rigidly mounted at one end in any suitable manner on the end of the screw shaft 2 as indicated at 1S, and is arranged to surround and normally enclose the screw shaft, control nut and pinion assembly. A mesh-enforcing spring 16 is located within the sleeve 9 between the pinion and control nut, the expansion of the spring being limited by a stop and bearing ring 17 xedly mounted on the free end of t-he sleeve.

A thimble 18 is mounted in the open end of the barrel 14, being retained therein by a lip 19 on the end of the barrel. A llanged liner sleeve 21 is seated in the barrel against the thimble and bears at its other end against yan abutment ring 22 which is retained in position against the flange of the liner by means of lugs 23 partially sheared and bent inwardly from the body of the barrel.

The abutment ring 22 is so located as to engage a radial flange 24 on the bearing ring 17 to thereby limit the meshing movement of the sleeve 9 and the pinion 4.v

:Means for yieldingly arresting the movement of the control nut in the meshing direction is provided comprising a cylinder 25 of elastically deformable material such Y An antiadrift spring 28 Vis'mounted at one end on the-- bearing ring 17 and at its vother end on the thrust ring 27. Y Preferably the anti-drift spring has a bearinglit'within f the abutment ring 22 of the barrel so that the free end of the sleeve has a steadying bearing through the bearing ring 17 and abutment ring 22 within .the barrel when the parts are in cranking position as shown in Fig. 2.

4In operation, starting with the parts in the position illustrated in Fig. 1, rotation of the power shaft 1, imparted by the pin 3 to the screw shaft 2, causes the control nut 8 to be traversed to theright, pushing the .pinion 4 and sleeve 9 ahead of it by means of the mesh-enforcing spring 16. When the teeth of the pinion are properly aligned with the tooth spaces of the engine gear 6, meshing movement proceeds until the bearing ring 17 engages the abutment ring 22 in the barrel. rPhe control nut 8 continues its longitudinal movement, compressing the elastic member 25 as shown in Fig. 2 until suicient torque is built up to crank the engine. During cranking, the pinion is supported not `only by the reduced section of the motor shaft on which it is journalled, but also by its connection to the sleeve 9 which at this time is supported at both ends in the barrel 14 by means of the thimble 18 and the stop ring 17 respectively. 'In some cases the desired gear ratio between the starting motor shaft and engine gear is so high that the pinion must be made solid in order to have the requisite -mechanical strength. The power shaft 1 is then terminated adjacent the idle position of the pinion, and the sleeve 9 arranged to be the sole support of the pinion.

When the engine starts, the parts are returned to normal position by the overrunning action of the engine gear, assisted by the pressure of the anti-drift spring 28 which thereafter maintains the parts in idle position.

Although but one embodiment of the invention has been shown anddescribed in detail it will be understood that changes may be made in the design and arrangement of the parts without departing from the spirit of the invention.

I claim:

1. In an engine starter drive, a power shaft, a screw shaft xed thereon, a pinion movable into and out of mesh with a gear of the engine to be started, a control nut threaded on the `screw shaft, a sleeve anchored at one end to the pinion and having a splined connection to the control nut, a mesh-enforcing spring between the pinion and control nut, a bearing ring fixed on the free end of said sleeve, a barrel member surrounding the control nut and sleeve and fixedly mounted at one end on the screw shaft, said barrel member having an abutment in the path of movement of the bearing ring to define the meshed position of the pinion and sleeve, and yielding means in the barrel member resisting the meshing movement of the control nut. Y

2. An engine starter drive as set forth in claim l in which the yielding means comprises an annular elastic member -in the free end of the barrel member, a thimble Patented Sept. 9, 1958" 3. An engine starter drive as set forth in claim 2 includ-- ing4 further an anti-drift spring between the bearing ring on the pinion sleeve and said elastic member.

4. In an engine starter drive, a screw shaft, a control nut threaded thereon, a sleeve splined on the control nut,

a` barrel member rigidly mounted at one end on the screw 10 shaft and surrounding said sleeve, a thimble xed in the free end of the barrel and bearing on the sleeve, an elastic cushioning member seated in the thimble, a thrust connection from the control nut to the cushioning member,

a pinion rigidly mounted on the sleeve adjacent the bear- 15 ing thimble, and yielding means transmitting longitudinal movement ofthe control nut to the pinion.

5. An engine starter drive as set forth in claim 4 including further an annular abutment in said barrel member,

and a stop and bearing ring on the sleeve engageable with 20 2635471 said abutment to dene the operative position of the sleeve and pinion.

6. An engine starter drive as set forth in claim 5 in which the stop and bearing ring is xedly mounted on the end of the sleeve remote from the pinion, and has a bearing in the annular abutment in the barrel member when the pinion is in operative position.

7. An engine starter drive including a screw shaft, a control nut threaded thereon, a sleeve splined on the control nut extending beyond the end of the screw shaft, a pinion iixedly. mounted in the extending end of the sleeve; a barrel member fixedly mounted on the screw shaft, means including an labutment and bearing member rigidly mounted in the barrel for arresting the meshing movement of the sleeve and pinion, and separate means in the barrel for yieldingly arresting the meshing movement of the control, nut.

References Cited in the file of this patent UNITED STATES PATENTS Lewis Apr. 23, 1953 2,643,548 Miller June 30, 1953 

